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redis-lite

redis-lite

redis-lite is a lightweight redis client for Node.JS with consistent hash clustering / sharding. Eventually, it'll support the redis cluster implementation.

  • Distributes keys over multiple redis servers using a consistent hashing algorithm.
  • Auto reconnect / failover mechanisms built in.
  • Pipelines requests for improved throughtput.
  • Can pool connections.

install

npm install redis-lite

connecting

var redis = require("redis-lite");
var client = redis(servers, options);

servers

The server list can either be a string, array, object or a function.

  • string: single server. use hostname:port or hostname for default port.
  • array: array of strings, keys will be distributed over these hosts.
  • object: different weights for different servers. {"hostname1": 1, "hostname2": 2} will cause hostname2 to have twica as many load as the hostname1.
  • function: an async function that should call the supplied callback with a server list. list can be in any format described above. this should be used for discovery purposes. let's say you need to query aws api to gather all instances running redis, you can do it with this method. redis(function(next) { next(null, "localhost"); })

options

  • socketNoDelay: (default: true) set no delay setting on underlying sockets. set false to improve throughput but that would increase latency.
  • socketKeepAlive: (default: true) enable keep alive functionality on underlying sockets.
  • retryDelay: (default: 2000) wait milliseconds before trying to reconnect a failed server connection.
  • removeTimeout: (default: null) wait milliseconds before marking a server dead and removing it from distribution. this will cause the keys on this server to be shifted onto others. by default, unavailable servers will be tried indefinately for reconnection.
  • replacementHosts: (default: []) supply additional hostnames for failover. this setting requires a removeTimeout duration, however, client will replace dead servers with one from this list instead of simply removing them.
  • connectionsPerServer: (default: 1) use n connections for each server. note that the client already does pipelining on a single connection, you do not need a lot of connections.
  • enableOfflineQueue: (default: true) if there is no active connection to a specific server, queue commands until we can acquire one.
var client = redis("localhost:6379", { retryDelay: 5000, removeTimeout: 20000 });

commands

Redis commands can be invoked directly on the client like this:

client.get('key', function(err, data) {
  ...
});
 
client.set('key', 'value', function(err) {
  ...
})
 
client.set(['key', 'value'], function(err) {
  ...
})

redis-lite will find the appropriate server for a given command and execute it.

author

Ekin Koc

license

MIT